Heretofore valve assemblies of the present type have been complex in construction providing numerous annular rings, spacers and O-ring SEALS stacked inside the valve body to provide chambers and passageways with seals for a slidable spool movable therein. To provide for greater tolerance between the spool and valve body, required a series of annular sealing members mounted upon the spool for cooperative registry with the bore as the spool is selectively moved to various control positions for regulating the flow of pressure fluids through the valve body.
In cases where the valve body is secured upon a support, fastening pressure often created warping of the valve body. Without suitable clearance between the spool and body, the spool would cease to be slidably positioned within the valve body either by air pressure or by spring loading.
An example of such prior art construction is shown in U.S. Pat. No. 3,017,901 dated Jan. 23,1962. This patent discloses the use of numerous annular rings, spacers and O-ring seals forming a part of the bore for receiving the loosely disposed valve spool and wherein numerous wiping seals are required to be mounted upon the spool to maintain a seal between the spool and the bore defined during movement of the spool into various control positions.